[tor-bugs] #5460 [Tor Client]: Write proposal(s) to evaluate circuit crypto authentication

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#5460: Write proposal(s) to evaluate circuit crypto authentication
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 Reporter:  mikeperry   |          Owner:  nickm             
     Type:  defect      |         Status:  assigned          
 Priority:  major       |      Milestone:  Tor: 0.2.4.x-final
Component:  Tor Client  |        Version:                    
 Keywords:              |         Parent:  #5456             
   Points:              |   Actualpoints:                    
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Comment(by arma):

 Replying to [comment:1 rransom]:
 > BEAR/LION/LIONESS are not ‘self-authenticating crypto’.  They are large-
 block block ciphers which ensure that any change to a block's data on one
 side of an honest relay completely scrambles the block's data on the other
 side.  They would need to be accompanied by an end-to-end MAC.

 Even if accompanied by an end-to-end mac, isn't that insufficient? If I
 can mangle a cell, and detect mangling, and it still gets to the other
 end, that sounds like a tagging attack to me. It's not as fine-grained a
 tagging attack sure, but if the goal is "cause circuit failure at the 2nd
 hop, not the third" then it's not going to do it, right?

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/5460#comment:5>
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